The present invention generally relates to highspeed search system in rotary recording medium reproducing apparatuses, and more particularly to a high-speed search system in an apparatus which reproduces a rotary recording medium recorded with a chapter address signal having a program number for every program unit of a recorded information signal, which is capable of searching for and obtaining a desired position within a predetermined program within a short period of time with high accuracy.
Systems have been realized in which a recording system forms pits in accordance with information signal being recorded along a spiral track on a flat rotary recording medium (hereinafter referred to as disc), without forming a groove therein, and a reproducing stylus traces over along this track to reproduce the recorded information signal in response to variations in the electrostatic capacitance in a reproducing system.
In this system, since no groove is provided on the disc for guiding the reproducing stylus, pilot or reference signals are recorded on or in the vicinity of a track of the information signal, such as a video signal, on the disc. Upon reproduction, the reference signals are reproduced together with the video signal. Tracking servo control is carried out so that the reproducing stylus accurately traces along the track in response to the reproduced reference signals.
In the above disc, only one of a first and second reference signals fp1 and fp2 is recorded at an intermediate position between center lines of adjacent track turns. Moreover, the side on which the first and second reference signals are recorded with respect to one track turn changes over every one track turn. That is, when the first and second reference signals are respectively recorded on the right and left sides of one track turn, the relationship between the recorded positions of the reference signals in such that the second and first reference signals are respecively recorded on the right and left sides of adjacent track turns. Furthermore, a third reference signal for obtaining a changeover signal upon reproduction, is recorded for every track turn at recording changeover positions of the above first and second reference signals.
In a reproducing apparatus, a changeover operation is performed by use of the third reference signal reproduced upon obtaining of a tracking control signal from the reproduced first and second reference signals.
Since no grooves are provided in the above disc, the reproducing stylus can be transferred from one track to another without damaging the reproducing stylus or the disc. Accordingly, in addition to the special reproduction such as still reproduction, slow-motion reproduction, and quick-motion reproduction, the system is capable of performing a so-called random access high-speed search in which the reproducing stylus is transferred to a desired position at high speed to reproduce the desired information.
Conventionally, in order to perform the above high-speed search and the like, address signals were continuously recorded in a recording region of the disc from the outermost periphery to the innermost periphery of the disc. Howeveer, by providing these address signals, there was a disadvantage in that the number of bits required became large. Accordingly, in order to eliminate this disadvantage, a system was considered in which a chapter address is used. This chapter address includes a program address indicating a program number for every program unit of the information signal, and a local address indicating a position within each program. By use of this system, the number of bits required can be reduced.
On the other hand, it is essential that the high-speed search is performed quickly and accurately. Hence, the present invention was devised in order to satisfy the above described demands in a disc which is recorded with the above chapter address signal.